Electrically-operated roasting spit



Dec, 3, 1929. M H SPIELMAN 1,738,328

ELECTRICALLY OPERATED ROASTING SPIT Original Filed Feb. 13, 1926 WW W Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE MILTON H. SPIELMAN, OF SHAKER HEIGHTS VILLAGE, OHIO, ASSIGNOR TO BORN STEEL RANGE COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO ELECTRICALLY-OPERATED ROASTING SIPIT Application filed February 13, 1926, Serial No. 87,997. Renewed May 2, 1929.

This invention relates to an electrically operated mechanical spit in a roasting device, the heat being supplied from heating coils adjacent the spit and energized by electric current. The object of the invention is to so arrange the electric circuit for the heaters and the motor that the motor may be materially cheapened and made more effective for operation at uniform speed under variable loads.

lln the operation of such a spit, it is desirable to use a low speed, low power motor and the load on the spit is seldom, if ever, uniform and it is very slowly revolved. The load varies with each revolution and a shunt motor for such a purpose is desirable, but not adapted for the conditions, and a series motor will vary in speed as the load varies during each revolution. Therefore, a more specific object of the present invention is to connect a portion of the heating elements in series with the field and get-ting the amountof current required by the armature by con necting the armature circuit into the clrcuits for the heaters in such manner that it is only necessary to use a very small number of turns in the field and a small number of turns in the armature for a very slow motor. A still more important object is to provide a universal motor having shunt characteristics which shall be steady in its operation regard less of the load as though it were a larger direct current shunt motor.

I am aware of shunt arrangements including resistance in the field circuit, but the present invention is for a movable device carrying material to be heated and driven by an electric motor, the electric motor having the characteristics herein described by reason of connecting the coils of the motor with certain of the heater coils as resistance elements and giving one characteristic to the field and another to the armature. As above indicated, experience has proven that such a mo tor may be made capable of delivering sufli-' cient power very much more cheaply than either a standard series or shunt motor type.

My invention is further described in connection with the accompanying drawing and the essential characteristics are summarized in the claims.

The drawing is a diagrammatical view of a spit and heater associated therewith illustrating the circuit arrangement for the motor.

Referring to the drawing with the use out numerals, the in-put circuit lines are indicated at 1 and 2 and ordinarily this supply is the usual 110 volt service current which is usually, but not always, alternating. 3 and 4 are suitable heating coils which may be mounted in any suitable fashion such for example as illustrated in the Patent No. 1,541,- 472 to William F. Born. 5 indicates the shaft of a spit having suitable food securing hooks 6 and 7. Tndicated in broken lines 8 is a fowl, mounted on the spit and subjected to heat from the heaters 3 and 4:, which, of course, may be arranged in any suitable positions and of which there may be any desired number. The shaft 5 may be driven by a reduction gearing indicatedat 1O operated by the armature shaft 12 of the motor whose armature is indicated at 13 having armature brushes 14: and a field indicated at 15. The circuit passes from line 1 through one heating coil 3 to the line 20 and through the field 15 to a dividing point. From this oint part passing through the armature brus' es 14 and the armature 13 to the line 21 to the mainline 2, the other part passing from the dividing point via the line 22 through the heating coil 4 of the line 2, this heating coil 4 being thus in a shunt across the armature.

In the circuit shown the current flowing through the field 15 will be the current in the heater 3, which equals the current in heattit) er 4 plus the armature current. For a given approximately 10 turns of wire or an equivalent of 90 or 100 ampere turns is suflicient to provide the ower necessary to turn a spit, through a re uction gearing such as shown, at say 2 to 4 revolutions per minute and that in operation very uniform speed is delivered to the spit regardless of eccentricity of load and corresponding change of load on the motor.

It is obvious that any form of carrier for the food or other thing to be heated may be used as is set forth in the above mentioned Born patent.

Having thus described my-invention what I claim is: I

1. In a device of the character described,

' the combination of electric heating coils, a

movable member adapted to carry the material to be heated, a motor for driving said movable member, means for supplying a current to the heating coils, and means for passing such current through the field of the motor and a circuit including substantially half]- of the coils only and the armature in para e 2. In a device of the character described, the combination of heating coils, service lines leading thereto, a carrier for the material to be heated, a motor for driving the carrier, the field of the motor being included in the circuit with all the heating coils, and the armature being shunted across a lesser number of the heating coils, whereby the current supply to the armature is cut down and whereby the motor tends to run at a constant speed under varying loads, the carrier and heaters being so related that the heater may heat material carried by the carrier.

3. In a device of the character described, the combination of heating coils, service lines leading thereto forming a circuit, a roasting v apparatus including a spit revoluble on an axis parallel with the axis of the heating coils, a motor drivingly connected with the spit and having a field and armature, the field of the motor being included in the circuit with the heating COIlS and the armature being included in .parallel with a portion of the heating coils, whereby part 0 the current is shunted past the armature, the spit and heating coils being so related that the coils may roast the thing to be carried by the spit.

4. In combination with a revoluble roasting spit, a plurality of electric heating coils arranged to heat material carried by the spit,

a motor having a comparatively small number of field turns of wire in circuit with the coils, and an armature the turns of which are shunted across part of the heatin coils whereby substantially constant speed characteristics are obtained for a small motor which shall be capable of steadily turning the spit irrespective of eccentricity of load on the s it.

5. n combination, a member adapted to carry material to be heated, a motor for driving said member and having a field and an armature, resistance heating coils positioned to act on such material, a subsidiary circuit comprising part of the resistance and the armature in parallel, and a major circuit includmg the field, the remainder of the resistance and the said subsidiary circuit.

6. In a roaster, the combination of a carrier for material to be heated, a series motor for driving said carrier and having a field and an amature and a heater unit in series therewith and another heater unit shunted across the armature, both heater units being positioned in proximity to said carrier so as to act on said material.

7. In combination, a carrier adapted to carry material to be heated, a motor having a field and an armature connection in series, a unit of fixed resistance shunted across the armature whereby the field current exceeds the armature current and decreases at a lesser rate than the armature current when the load decreases, and an electic heating element in series with the field and armature and adapted to act on the material on the carrier.

8. In combination, a spit adapted to carry an eccentric load of material to be heated, a motor having a field and an armature connected in series, and a heating unit of fixed resistance located adjacent to the spit and shunted across the armature whereby the field current exceeds the armature and current and decreases at a lesser rate than the armature current when the load decreases.

In testimony whereof, I hereunto afiix my 

